(1) Field of the Invention
The invention relates to an autonomous power supply system which supplies electric power to electronic equipment using a power generation element.
(2) Description of the Related Art
In the case where the electronic equipment is installed in an isolated place with difficulty in receiving power supply, it is effective to employ the autonomous power supply system provided with a power generation element such as a solar cell so as to allow unmanned operation without receiving power supply from external commercial power source. JP-A-2010-104117 discloses the above-described power supply system which enables extraction of electric power from the solar cell with high efficiency even if the period of daylight in cloudy weather frequently fluctuates. JP-A-2010-104117 discloses that any one of the storage battery and a plurality of capacitors (capacitor module), which constitute the power storage device is charged with electric power generated by the solar cell in accordance with the insulation fluctuation, and the capacitors are switched in sequence by calculating the time for charging the capacitor from the charging current that can be extracted from the solar cell.